I would like to stop the execution of a process and FASTAPI with Ctrl+C in Python. But I recieving error KeyboardInterrupt exceptions, how to properly stop threads and FAST API

from fastapi import FastAPI
import threading
import time
import signal
from datetime import datetime, timedelta

from model import core
from model.database import engine, SessionLocal, get_db
from model.core import Timestamp
from routers.timestamps import router as timestamps_router

core.Base.metadata.create_all(bind=engine)

app = FastAPI()

app.include_router(router=timestamps_router)

def record_timestamp():
    while True:
        db = SessionLocal()
        new_timestamp = Timestamp(timestamp=datetime.utcnow())
        db.add(new_timestamp)
        db.commit()
        db.close()
        time.sleep(5)


def delete_old_timestamps():
    while True:
        db = SessionLocal()
        one_minute_ago = datetime.utcnow() - timedelta(minutes=1)
        db.query(Timestamp).filter(Timestamp.timestamp < one_minute_ago).delete()
        db.commit()
        db.close()
        time.sleep(10)


@app.on_event("startup")
def startup_event():
    get_db()
    t1 = threading.Thread(target=record_timestamp)
    t2 = threading.Thread(target=delete_old_timestamps)

    t1.start()
    t2.start()

    t1.join()
    t2.join()

i triend to wite a signal with ChatGPT but also had failed